Methods of and apparatus for connecting a strand and an elongated member and methods of manufacturing such apparatus



Oct. 26, 1965 J. o. ETCHISON, JR.. ETAL 3,213,894

METHODS OF AND APPARATUS FOR CONNECTING A STRAND AND AN ELONGATED MEMBERAND METHODS OF MANUFACTURING SUCH APPARATUS Filed Oct. 15, 1962 5Sheets-Sheet 1 5/ I 3/ if I 5 ATTORNEY Oct. 26, 1965 Flled Oct 15 1962 42 9 om m 1 w 2 N S D e N h A S R T 3 SF 0 L SS DU J. O. ETCHISON, JR. E

METHODS OF AND APPARATUS FOR CONNECT AN ELONGATED MEMBER AND METHOMANUFACTURING SUCH APPARAT mi mm m. M 0 a h a ATTORNEY Oct 1965 J. o.ETCHISON, JR.. ETAL 3, 3,

METHODS OF AND APPARATUS FOR CONNECTING A STRAND AND AN ELONGATED MEMBERAND METHODS OF MANUFACTURING SUCH APPARATUS Filed Oct. 15, 1962 5Sheets-Sheet 3 INVENTORS //7//z .zaaflazzah m, J2:

ATTORNEY United States Patent METHODS OF AND APPARATUS FOR CONNECT- IN GA STRAND AND AN ELONGATED MEMBER AND METHODS OF MANUFACTURING SUCHAPPARATUS John O. Etchison, Jr., Clemmons, and Jack C. Hetherington,Greensboro, N.C., assignors to Western Electric Company, Incorporated,New York, N.Y., a corporation of New York Filed Oct. 15, 1962, Ser. No.230,759 16 Claims. (Cl. 14093.6)

This invention relates to methods of and apparatus for connecting astrand and an elongated member and to methods of manufacturing suchapparatus. More particularly, this invention relates to methods of andapparatus such as a bit for wrapping wire strand on a terminal, and tomethods for manufacturing such apparatus.

In the manufacture of electrical units, it is sometimes necessary toconnect strands to elongated members. More particularly, in themanufacture of electrical units such as printed circuit boards,telephone terminal banks used in the communications field, etc., it isnecessary to wrap strands such as electrically conductive filaments,wire, or metal terminals, extending from a component, onto elongatedterminals mounted on the printed circuit board, terminal bank, etc. tomechanically and electrically connect the strand to the terminal.

In the past, apparatus for connecting a strand and an elongated membersuch as a terminal, has included a generally cylindrical bit having alongitudinal recess extending from an end surface into the bit forreceiving the terminal. Such prior apparatus has also been provided witha longitudinal groove machined in the outer peripheral surface of thebit. The longitudinal groove intersects and forms a corner with the endsurface to direct strand onto the terminal during a wrapping operation.

In the use of such prior apparatus, a tubular sleeve is mounted over thebit and the bit and the sleeve are mounted on a rotary spindle. The bitis placed over the terminal so that the terminal extends into thelongitudinal recess. A strand, such as wire, is fed into the groove withan end portion thereof extending out of the groove and temporarilysecured to the terminal. To commence wrapping, the spindle is driven forrotating the bit and the sleeve so that the longitudinal groove rotatesaround the terminal. As the bit rotates, the wire advances out of thelongitudinal groove in the direction of the axis of the terminal. Theaxially advancing wire is engaged and thrust transversely to the axis ofthe terminal by the corner of the longitudinal groove and is therebywrapped in the form of convolutions onto the terminal. As theconvolutions are wrapped, the last-wrapped convolution urges the bit offthe terminal in opposition to a force known as the back force--that isapplied to the bit through the spindle.

Two principal criteria have been established for deter mining thequality of wrapped connections between wires and terminals. First, theconnection must not advance axially relative to the terminal during astrip test wherein measured forces are applied to the wire in thedirection of the axis of the terminal. Secondly, the wire must not breakor fail during an unwrap test wherein the wire is unwound from theterminal.

Testing connections wrapped by the prior bits in view of these criteria,indicates that significant problems accompany the use of the prior bits.More particularly, the tests indicate that the back force applied to thebit must be carefully regulated because increases in the back forcecause the wire to be wrapped too tightly on the terminal. When the wireis wrapped too tightly on the terminal, the corners of the terminal biteinto the wrapped convolutions to such an extent that the connectionfails the unwrap test.

Accordingly, prior efforts have been directed toward decreasing the backforce in an attempt to preclude failures during the unwrap test. Whenthe back force is significantly reduced. it has been found that theprior bits wrap convolutions having a nearly perfect circularconfiguration. As a result, only four small points of each circularconvolution of wire contact the terminal, rendering the connectionlikely to fail the strip test. To increase the amount of contact betweenthe wire and the terminal by means other than varying the back force,projections are generally formed on the end surface of prior bits. Theseprojections are provided with what is known as wiping surfaces, whichrotate with the bits, engaging and pressing the wrapped convolutions ofwire onto the terminal. The wiping surfaces are effective to force thewire against the corners of the terminal and increase the amount ofcontact between the wrapped wire and the terminal. However, experienceindicates that the wiping surfaces, by impressing the circularconvolutions of wrapped wire onto the terminal, create cuts in thecircular convolutions of wire which appear to be additional causes offailures during the unwrap test.

Additionally, as a result of the tests made in view of theabove-mentioned criteria on connections wrapped by the prior bits, it isbelieved that the corners of the prior bits, formed by the intersectionof the longitudinal grooves and the end surfaces, work-harden the wireand render the wire subject to cracking as it is wound onto the sharpcorners of the terminal. Failures are believed to occur during theunwrap test because of this work-hardening and cracking. Also, thefriction that occurs at the corners during the work-hardening isbelieved to cause erosion of the corner and consequent roughening andscratching of the surface of the wire. Because of the erosion of thecorner, the average life of such wrapping bits has been found to be onlysix to seven days, during which an approximate average of only 6,000connections have been wrapped. The eroded bit must be reworked to makethe corner smooth, or if the erosion is too severe, the bit discarded.

Problems have also arisen in attempting to prevent such wear and erosionof the corner of the longitudinal groove. Hardening processes, such ascarbonizing, which have been performed at the corner, have beenineffective to significantly increase the life of the bit, whilerendering such bits extremely costly. Accordingly, excessive bitreworking and replacement is necessary, rendering the use of such priorwrapping bits very expensive.

Research has been conducted to determine the source of theabove-mentioned problems in an endeavor to provide a simple andinexpensive wrapping bit having characteristics of long life and freedomfrom the abovementioned problems and limitations. During such research,close examination has been given to the details of the wire wrappingoperation. In this examination, it has been discovered that the axialand transverse components of motion of the wire advancing out of thelongitudinal groove, resolve according to the characteristics of thewire so that the wire assumes an arcuate path between the corner of thelongitudinal groove and a first point of contact with the terminal. Moreparticularly, it has been discovered that the wire naturally assumes anarcuate path which has a predetermined radius of bend, which ishereinafter termed the natural bending radius of the wire.

As a result of the discovery of this natural bending radius, the sourceof the limitations and problems attendant use of the prior bits has, forthe first time, been discovered. Thus, it has been found that byproviding, at a predetermined location on the bit, an arcuate strandforming surface having the natural bending radius of a strand to bewrapped, the problems attendant prior bits are reduced to insignificantproportions. Moreover, connections wrapped by bits provided with suchforming surfaces, withstand extraordinarily high forces during the striptest, while passing the unwrap test.

Significantly, experiments conducted with bits manufactured according tothe principles of this invention, indicate that the bits are capable ofwrapping acceptable connections for at least seventy-two working dayswithout showing signs of wear or erosion. Also, it has been determinedthat back force is not critical to the wrapping of acceptableconnections with the bits of the present invention, and that lessmarring of the wire is evident because of the natural flow of Wirearound and in continuous contact with the forming surface of the bits ofthe present invention.

No less important, it has been found that bits embodying the principlesof the present invention wrap connections which are highly stable. Thatis, four convolutions of a six convolution wrapped connection may beunwrapped from the terminal before the remaining two convolutions willrotate relative to the terminal. Furthermore, simple and inexpensivetechniques may be employed to manufacture the present bits frominexpensive stock material, rendering costly material and hardeningoperations unnecessary An object of the present invention is to providenew and improved methods of and apparatus for connecting a strand and anelongated member.

Another object of the present invention is to provide a simple andinexpensive apparatus and method of manufacturing such apparatus forwrapping wire strand onto a terminal.

Still another object of the present invention is to provide new andimproved wire wrap-ping facilities for producing a connection between awire and a terminal wherein the quality of the connection issignificantly increased.

An additional object of this invention resides in the provision of anapparatus and methods of making such apparatus for wrapping wire strandonto a terminal wherein the apparatus is provided with characteristicsof long life and freedom from limitations and problems attendant priorwrapping apparatus.

A further object of this invention resides in a Wire provide a wireguide groove having a radius corresponding to the natural bending radiusassumed by the wire during wrapping.

A still further object of this invention is to provide an elongated wirewrapping facility having an end surface and a longitudinal groove forsupplying wire along an arcuate surface that undercuts the periphery ofthe facility wherein the surface is provided with a predetermined radiusand formed tangent to the groove and the end surface.

A related object of this invention resides in the provision of auniversal bit for wrapping wires having various diameters wherein thebit is provided with a wire forming surface for engaging an entiresection of the wire that naturally assumes a predetermined curvedconfiguration during wrapping onto a terminal.

With these and other objects in view, the present invention contemplatesapparatus such as a bit for conmeeting a strand and an elongated membersuch as a terminal according to one method of the present invention. Thebit is provided with a fiat end surface and a recess extending from theend surface into the bit for receiving the terminal. A longitudinalgroove machined in the peripheral surface of the member extends towardthe end surface. A strand forming surface is formed in the bit tangentto both the recess and the end surface and extends arcuately under theperiphery of the bit into tangential intersection with the groove. Thearcuate configuration of the strand forming surface corresponds to thenatural bending radius assumed by the strand during wrapping.

Additionally, with the foregoing objects in view, the present inventioncontemplates a method of manufacturing apparatus, such as a bit, forwrapping strand onto a terminal wherein the strand during the wrappingnaturally assumes a curved configuration having a predetermined naturalbending radius. A workpiece, such as a bit blank, is provided with anend surface, a terminal receiving recess extending from the end surface,and a longitudinal groove formed in the periphery of the blank andterminating at the end surface. The natural bending radius of the strandis determined. Then a strand forming surface is formed in the bit blanktangent to both the recess and the end surface and extending arcuatelyinto tangential intersection with the longitudinal groove. The arcuateconfiguration of the surface is formed in conformity with the naturalbending radius of the strand.

A complete understanding of this invention may be had by reference tothe following detailed description when read in conjunction with theaccompanying drawings illustrating preferred embodiments thereof,wherein:

FIG. 1 is a perspective view of an apparatus of the present inventionmanufactured according to one method of this invention for wrappingstrands such as wire onto terminals according to another method of thisinvention, showing a bit provided with an arcuate strand guideway havinga radius conforming to the natural bending radius of the strand;

FIG. 2 is an elevational end view of the bit shown in FIG. 1illustrating the bit rotating to advance a strand through the guidewayand onto a terminal received in a recess provided in the bit;

FIG. 3 is a view similar to FIG. 2 showing a convolution of strandwrapped in a generally square configuration on the terminal upon furtherrotation of the bit;

FIG. 4 is a plan view of the bit shown in FIG. 1 illustrating alongitudinal groove formed in the bit tangent to the arcuate guidewayfor guiding a strand to the arcuate guideway during a wrappingoperation;

FIG. 5 is a cross-sectional view taken on line 5-5 0 FIG. 2 showing aforming surface of the strand guideway having the natural bending radiusof the strand and formed tangent to the end surface of the bit andtangent to the strand groove;

FIG. 6 is an end view of the bit shown in FIG. 1 provided with referenceletters designating various dimensions of the bit;

FIG. 7 is a cross sectional view taken on line 7-7 of FIG. 6 showing thestrand guideway having the natural bending radius of the strand .andformed tangent to the end surface of the bit and tangent to the strandgroove in conjunction with additional reference letters indicatingadditional dimensions of the bit;

FIG. 8 is a cross sectional view taken on line 88 of FIG. 6 illustratingthe transverse configuration of the forming surface of the strandguideway;

FIG. 9 is a perspective view of a bit blank which may be employed inpracticing the method of the present invention to manufacture a wrappingbit 'having the strand forming surface shown in FIG. 7;

FIG. 10 is an end View of a .prior b-it illustrating the generallycircular configuration of convolutions of wire wrapped by the prior bitin conjunction with sharp corners of the terminals which project intothe inner surfaces of the convolutions of the wire;

FIG. 1l-is a plan view of the prior wrapping bit shown provided with alongitudinal groove forming a corner at the intersection thereof with anend surface of the prior bit in conjunction with a projection having awiping surface for pressing the convolutions of wire into the terminal;

FIG. 12 is a plan View of the prior bit similar to FIG. 11 showingconvolutions of wire wrapped on the terminal While determining thenatural bending radius of the wire;

FIG. 13 is a cross sectional view of the prior bit taken along line 1313of FIG. illustrating the spacing of the end surface of the prior bitfrom the wrapped convolutions of wire in conjunction with the naturalbending radius of the wire;

FIG. 14 is an end view of another embodiment of the present inventionshowing a universal bit for wrapping various strands having differentdiameters onto a terminal and illustrating a terminal receiving recessformed eccentrically with respect to the center of the universal bit;

FIG. 15 is a cross sectional view taken on line 15'1'5 of FIG. 14showing a strand forming surface formed with the natural bending radiusprovided in the universal bit; and

FIG. 16 is a cross sectional view taken on line 16-46 of FIG. 14 showingthe transverse configuration of the strand forming surface provided onthe universal bit.

Prior wrapping tool A description of and the significant advantages ofthe present invention may best be appreciated by referring first toFIGS. 10 and 11, wherein .a prior or standard wire wrapping tool 20 isshown including a shaft or bit 21, which is sometimes referred to as aspindle or wrapping head. The prior bit 21 is received in a sleeve 22for rotation therewith under the action of a motor (not shown). The bit21 is provided 'with a central recess 23 extending axially from an endsurface 26 (FIG. 11) for receiving a terminal 27 having a longitudinalaxis 31. A groove 28 extending from the end surface 26 is formed in theperiphery of the bit 21. A corner 29 (FIG. 11) is formed by theintersection of the groove 28 and the end surface 26. A projection 32extending from the end surface =26 adjacent to the corner 29 is providedwith a sloped wiping surface 33.

In the operation of the prior bit 21, the terminal 27 is inserted in therecess 23, whereafter a length of strand, such as wire '34, is insertedin the groove 28. One end of the Wire 34 is then temporarily secured tothe terminal 27. The sleeve 22 and the bit 21 are then rotated as a unitrelative to the terminal 27. Upon rotation of the bit 21 and the sleeve.22, the wire 34 advances out of the groove 28 parallel to the axis 31of the terminal 27 and is directed by the corner 29 in a path that istransverse to the axis 31. The wire 34 advances in the transverse pathand is Wrapped on the terminal 27 in the form of helical convolutions 36having a helix or lead angle 37 (FIG. 13) and a generally circularconfiguration (FIG. 10).

During the wrapping operation, the end surface 26 of the prior bit 21 isspaced by a distance 38 from the last Wrapped convolution 39 of wire 34as shown in FIG. 13. Additionally, the corner 29 at the intersection ofthe longitudinally groove 28 and the end surface 26 engages a section 40of the wire 34 which is advancing in a direction parallel to the axis 31and which is remote from the last wrapped convolution 39. An arcuate ortransverse section 41 of the wire 34- is not engaged by the prior hit21, but is free and advances transversely onto the terminal 27 withoutadditional guiding forces being applied thereto by the prior bit 21.

Referring in detail to FIG. 10, the helical convolutions 36 Wrapped bythe prior bit 21 are shown having the generally circular configurationwhen viewed along the axis 31 of the terminal 27 'I he wiping surface 33of the projection 32 has engaged and pressed the wrapped convolutions 36against the corners 43 of the terminal 27 so that the corners cut intothe wire 34 to increase the amount of cont-act bet-ween the wire and theterminal. The Wiping surface 33 may also have been effective to pressiarouate sections 44 of the wrapped convolution 36 toward the sides 46of the terminal 27 as the wire 34 is forced against the corners 43 ofthe terminal. Thus the Square wrap bit Attention is now directed to FIG.1 wherein there is shown an apparatus constructed according to theprinciples of the present invention for connecting a strand 51, such asan electrically conductive filament, wire, etc., and an elongated member52, such as a terminal. The app-aratus includes an elongated, generallycylindrical, squarewrap bit 53 having a central longitudinal axis 54. Arecess 58 having a generally cylindrical wall 59 extends from a flat endsurface 57 parallel to the axis 54 into the bit 53 for receiving theterminal 52. A longitudinal groove 62 is formed in the outer peripheralsurface 63 of the bit 53 and extends from the end surface 57 in thedirection of the axis 54. The longitudinal groove 62 is formed so thatthe surface 64 thereof has an arcuate cross-section. Adjacent to theintersection or junction of the longitudinal groove 62 and the endsurface 57, there is provided .a Wrapping section or a strand formingsurface 66, etc., that extends :arcuately from the longitudinal grooveinto intersection with the end surface 57. The arcuate configuration orcontour of the forming surface 66 is formed in conformity with andcongruent to the natural bending radius 68 (FIGS. 5 and 7) of the strand51 that is to be wrapped and connected to the terminal 52.

Considering the forming surface 66 in further detail by reference toFIGS. 1 and 4, provision of the forming surface 66 in the bit 53 isshown to be effective to form an arcuate or curvilinear slot or guideway67 having the arcuate forming surface 66 as a lower surface. The formingsurface 66 and the guideway 67 undercut the periphery 63 of the bit 53and form a lip 71. More specifically, and now referring also to FIGS. 5and 6, the forming surface 66 is shown formed tangent to both the endsurface 57 and the wall 59 (FIGS. -1 and 6) of the cylindrical recess 58and extends into tangential intersection with the longitudinal groove62.

In operation, the bit 53 is enclosed in the tubular sleeve 22 (FIGS.2-4) that is provided with an inside diameter equal to the outsidediameter of the bit 53. The terminal 52, which may be mounted againstrotation on a support (not shown), and the enclosed bit 53 are movedaxially relative to each other to insert the terminal 52 in thecylindrical recess 58. Next, a length 72 (FIGS. 4 and 5) of the wire 51is inserted through the guideway 67 around the forming surface 66 foradvancement axially into the longitudinal groove 62. A trailing end 73(FIG. 2) of the wire 51 is then temporarily secured to the terminal 52and the bit 53 and the sleeve 22 are rotated relative to the terminal.As shown in FIGS. 2 and 4, as the bit 53 and the sleeve 22 rotate, thewire 51 advances through the longitudinal groove 62 toward the formingsurface 66 and the terminal 52 in the direction of the longitudinal axis54 of the bit. A section 76 (FIGS. 3-5) of the axially advancing wire 51is engagedby the forming surface 66 and is thrust thereby transverselyto the axis 54 of the bit into a predetermined arcuate configuration.The transversely thrust arcuate section 76 of wire 51 advances aroundand in continuous contact with the forming surface 66 into contact withthe flat end surface 57 (FIG. 5). The Wire 51 advances along the flatend surface 57 onto the terminal 52 in the form of generally squareconvolutions 77 of wire as shown in 'FIG. 3. The engagement of the endsurface 57 with the wire 51 as the convolutions 77 are wrapped, iseffective to urge the bit 53 off the terminal 52 at a uniform rate sothat the convolutions 77 of wire are connected to the terminal atuniform helix angle 79 (FIG. 4).

By maintaining control of the transversely .advancing section 76 of wire51 just prior to the contact of the wire with the terminal 52, theforming surface 66 is effective to form the convolutions 77 in thegenerally square shape or configuration. Thus, as shown in-FIG. 2, afirst section 81 of the Wire has been laid nearly parallel to one side82 of the terminal 52. Referring to FIG. 3, a complete convolution 77 ofwire wrapped by the bit 53 is shown having four such sections 81 whichare wrapped closely parallel to the sides 82 of the terminal 52 and thusassume the generally square configuration.

The present invention includes a method of manufacturing the bit 53 forwrapping the wire 51 onto the terminal 52. The method utilizes thecharacteristic which the wire 51 has during wrapping of naturallyassuming an arcuate configuration having the natural and predeterminedbending radius 68 (FIGS. and 7). The method includes the steps ofproviding a bit blank 91 (FIG. 9) having the fiat end surface 57, thelongitudinal groove 62 formed in the periphery thereof, and the recess58 for receiving the terminal 52 which is to be provided in the bit 53.The method further includes the step of forming in the bit blank 91 asurface, such as the strand forming surface 66 shown in FIGS. 1 and 7,that extends arcuately from the longitudinal groove 62 into intersectionwith the end surface 57. The arcuate contour of the surface 66 conformsto the predetermined natural bending radius 68 of the wire 51.

Considering in further detail the strand forming surface 66, attentionis now directed to FIGS. 11, 12 and 13 for a description of a method fordetermining the natural bending radius 68 (FIG. 13) of the wire 51(FIG. 1) or wire 34 that is to be Wrapped by the bit 53 provided withthe forming surface 66.

Initially, as shown in FIG. 11, the terminal 27 is in serted into therecess 23 of the prior bit 21 which has been enclosed by the sleeve 22.A first length 96 of wire 34 is inserted into the longitudinal groove 28of the prior bit 21. A second length 97 of the wire 34 extending fromthe groove is temporarily secured to the terminal 27.

The bit 21 and sleeve 22 are then rotated relative to the terminal 27 asshown in FIG, 12 to wrap the convolutions 36 of wire onto the terminal.Bef-ore all of the first length 96 of wire 34 has been wrapped onto theterminal 27, for example, when four convolutions 36 have been wrapped onthe terminal, the rotation of the bit 21 and the sleeve 22 is suddenlystopped. As shown in FIG. 13, the bit 21 and the sleeve 22 are thenmoved in the direction of the arrow 98 to expose the first length 96 ofwire which extends in a path 99 parallel to the terminal 27. Alsoexposed, is the section 41 of the wire 34 which extends from theparallel path 99 arcuately onto the terminal. The radius 68 (FIG. 13) ofthe arcuate section 41, which is the natural bending radius of the wire34, is then measured and recorded.

The above steps are repeated for each wire 34 or 51 of various types andgages of wire that are to be wrapped, and the respective natural bendingradius 68 is formed on one of the bits 53 of the present invention.

The natural bending radius 68 determined by the above method may beprovided on the bit 53- according to the following detailed descriptionwhen considered in conjunction with FIGS. 6, 7, and 8. The descriptionrefers to certain dimensions of the bit 53 by means of reference lettersA through 1.

Referring first to FIG. 6, letter A represents the outside diameter ofthe bit 53. Letter B represents the diameter of the cylindrical recess58. The bit 53 of this example is provided with a longitudinal groove 62having a radius E formed in the periphery of the bit 53 at an angle Iand a distance C from the X axis 100. The center of the longitudinalgroove 62 also intersects a circular line 102 having a radius D. In thislocation, a line 103 drawn parallel to the X axis 100 and tangent to thewall 59 of the cylindrical recess extends into tangential engagementwith a wall 104 of the longitudinal groove 62.

As shown in FIG. 7, the forming surface 66 is formed tangent to thelower surface 106 of the longitudinal groove 62 and is provided with aradius F which is the natural bending radius 68 of the wire 51 to bewrapped onto the terminal 52. The arcuate forming surface 66 extendsparallel to the line 103 as viewed in FIG. 6 and tangentially intersectsthe fiat end surface 57 of the bit as shown in FIG. 7. As shown in FIG.8, the forming surface 66 tangentially intersects the end surface 57 andforms a wall 108 between the arcuate surface 66 and the wall 59 of thecylindrical recess 58.

Another aspect of the present invention contemplates a method ofconnecting the strand or wires 51 and the elongated member or terminal52. More particularly, the method of connecting the wire 51 and theterminal 52 is effective to wrap the wire onto the terminal according tothe principles of the present invention. The method utilize-s thecharacteristics of the wire 51, set forth above, of naturally assumingduring wrapping a predetermined arcuate path having the natural bendingradius 68 (FIGS. 5 and 7). In the practice of the method for connectingthe wire 51 and the terminal 52, the wire is advanced in the directionof the axis 54 of the terminal. The advancing wire 51 is engaged andthrust or directed transversely to the axis 54 to form the section 76(FIG. 3-5) having the predetermined arcuate configuration of the naturalbending radius 68. The section 76 of the wire 51 is then guided bycontinuously contacting the wire along the natural bending radius towrap the wire onto the terminal 52.

Another aspect of the present invention contemplates the provision of auniversal square wrap bit 111 that is adapted to wrap various gages andtypes of wire 51 onto the terminals 52. Referring to FIGS. 14, 15 and16, the universal bit 111 is shown generally cylindrical inconfiguration and has a central longitudinal axis 112 defined by theintersection of X and Y axes 114 and 116 respectively. A cylindricalrecess 117 is formed through the end surface 118 of the bit 111eccentrically with respect to and on one side 113 of the longitudinalaxis 112. The center 121 of the recess 117 may be located by passing aline 122 through the longitudinal axis 112 of the bit at an angle suchas 45 measured from the X axis 114. A distance such as 0.010 of an inchis then marked on a line 126 that is drawn perpendicular to the 45 line112 and passes through axis 122. The point defined by the intersectionof the parallel line 127 (drawn parallel to line 122) and the Y axis 116is the center 121 of the cylindrical recess 117.

A wire guide groove may be located on the other side 115 of the axis 112by drawing a line 131 through the center 121 of the recess 117 at anangle 130 such as 35 measured from line 127. A line 132, drawnperpendicular to the line 131 and tangent to the recess 117, extendsacross the end surface 118 of the bit into intersection with theperiphery 133 of the bit. A circle 134 having a diameter equal to thelargest diameter of wire 51 to be wrapped is positioned tangent to theline 132 and the periphery 133 of the bit 111. A section 136 of thecircle which extends between points 137 indicates the lower surface ofthe longitudinal wire guide groove 141 that extends in an axialdirection in the periphery 133 of the bit 111. As shown in FIG. 16 auniversal wire forming surface 142 is provided with the same transversediameter as the diameter of the wire guide groove 141. As viewed in FIG.16, the universal wire forming surface 142 is centered on a line drawnparallel to the line 132 (FIG. 14) and extends arcuately into tangentialintersection with both the end surface 118 of the bit 111 and the wallof the recess 117. Universal bits 111 constructed according to thepresent example have successfully wrapped wires 51 having such variousdiameters as 0.016, 0.020 and 0.025 of an inch according to the wrappingoperation described above for the bit 53 of the present invention.

In accordance with the method contemplated by the present invention formanufacturing a bit 53 (FIG. 1) for wrapping wire 51 onto a terminal 52,the bit blank 91 shown in FIG. 9 is enclosed with the tubular sleeve 22shown in FIG. 4, and a terminal 52 is inserted into the longitudinalrecess 58. A length of wire 51 is inserted into the longitudinal groove62 and the bit blank 91 and the sleeve 22 are rotated relative to theterminal 52 to advance the length of wire 51 from the groove around acorner 151 that forms the intersection between the longitudinal groove62 and the end surface 57 and onto the terminal 52. The wire formingsurface 66 shown in FIG. 7 may be provided in the bit 91 by applying anabrasive compound 153, such as diamond lapping compound number 40-W-30,sold under trademark Hyprez, to the advancing wire 51 and thelongitudinal groove 62 at a point 154. The compound 153 is effective toform the surface 66 (FIG. 7) in the bit blank 91 in conformity with thenatural bending radius 68 (FIG. 7) of the wire 51. Alternatively, and inaccordance with the method of making bits 53 contemplated by the presentinvention, the abrasive coating 153 may be provided on the periphery ofthe wire 51 for forming the wire forming surface 66 in the bit blank 91as the wire is wrapped onto the terminal 52.

According to a preferred method of manufacturing the bit 53 (FIG. 1)from a generally cylindrical bit blank 91 according to the principles ofthe present invention, the bit blank 91 (FIG. 9) is provided with thelongitudinal recess 58 and the longitudinal groove 62 extending towardthe flat end surface 57. The preferred method includes the provision ofthe prior bit 21 (shown in FIGS. 11-13) having the end surface 26. Theprior bit 21 is also provided with the longitudinal recess 23 extendingfrom the end surface 26 and the longitudinal groove 28 intersecting theend surface to form the corner 29. A portion of the terminal 27 isenclosed by inserting the terminal into the ecess 23 of the prior bit21, and the first length 96 of wire 34 is inserted into the longitudinalgroove 28. The second length 97, which is the leading end of the wire34, extends out of the longitudinal groove 28 and is temporarily securedto the terminal 27. The standard bit 21 and the terminal 27 are rotatedrelative to each other to advance a portion of the first length 96 ofthe wire 34- through the longitudinal groove 28, around the corner 29and onto the terminal 27. The relative rotation between the bit 21 andthe terminal 27 is suddenly interrupted so that a portion of the firstlength 96 of the wire 34 remains in the longitudinal groove. The portionof the first length 96 that advanced from the groove 28 extends in thearcuate path naturally assumed by the wire 34 as it advances around thecorner 29 toward the terminal 27 The radius of the arcuate pathnaturally assumed by the wire, i.e., the natural bending radius 68 ofthe wire 34 is then measured (FIG. 13). An arcuate surface 66 providedwith the natural bending radius '68 of the arcuate path of the wire 34is then formed in the bit blank 91 tangent to both the groove 62 and therecess 58 of the bit blank 91 as shown in FIGS. 6 and 7.

Although the bits 53 have been described in conjunction with terminals52 having a square cross-section, it is to be understood that the bits53 successfully wrap convolutions 77 of wire on terminals havingrectangular crosssections.

It is to be understood that the above-described arrangements are simplyillustrative of the application of the principles of this invention.Numerous other arrangements may be readily devised by those skilled inthe art which will embody the principles of the invention and fallwithin the spirit and scope thereof.

What is claimed is:

1. In a device for winding strand onto an elongated member,

bit means having a groove for maintaining the strand in an axial path,and

means formed in said bit means for directing the strand from said axialpath in an arcuate path congruent to the natural bending radius of thestrand onto said elongated member, said means having an effectivesurface corresponding to said arcuate path so that said surfacecontinuously engages the strand advancing in the arcuate path.

2. In a wrapping bit for providing a square-wrap coil of filament on aterminal having a square cross-section wherein the filament assumes apredetermined configuration during wrapping onto said terminal, saidconfiguration being congruent to the natural bending radius of thefilament;

an elongated member having a flat end surface, a peripheral groove forreceiving said filament, and a recess for receiving said terminal; and

means formed in the member tangent to said fiat end, the base of saidgroove, and said recess for defining an arcuate guideway having saidpredetermined configuration to form said square-wrap coil during saidwrapping.

3. In a bit for wrapping metal strand onto an article;

an elongated member having a transverse end surface, a shank section,and a wrapping section terminating at the transverse end surface; saidwrapping section being provided with a peripheral groove and an arcuateslot tangent to said groove and said end surface, said arcuate slothaving a configuration congruent to the natural bending radius of themetal strand.

4. In a bit for wrapping wire onto a terminal,

a cylindrical member having an end surface and a cylindrical recessextending from said end surface into the member, said member beingprovided with a wire guide groove having a first axially extendingsection provided with a first guide surface and a second transversesection having a second guide surface, said second guide surface havinga radius equal to the natural bending radius of the wire and beingformed tangent at one end to said first guide surface and tangent at theother end to both the end surface and said cylindrical recess.

5. In a device for wrapping a strand onto a terminal, said strand havinga characteristic of naturally assuming a predetermined natural bendingradius during wrapping,

a bit provided with a longitudinal axis and an end surface transverse tosaid axis,

means formed in the bit along said axis for receiving said terminal,

means formed in the periphery of said bit parallel to said axis forsupplying strand to be wrapped onto said terminal, and

means including an arcuate surface undercutting the periphery of saidbit, said arcuate surface having said predetermined natural bendingradius of the strand and formed tangent to both the strand supplyingmeans and to said end surface.

6. In a tool for connecting a wire and a terminal, a bit for winding thewire on the terminal upon relative rotation between the bit and theterminal,

said bit comprising a rod-like member having an end surface and alongitudinal recess extending from said end surface into the member forreceiving the terminal, said member having a longitudinal groove formedin the periphery surface of the member and extending from said endsurface, said member being provided with a guideway extending from saidgroove and terminating at said surface tangent to said recess and saidend surface, said guideway being provided with an arcuate bottom surfacehaving a radius substantially equal to the natural bending radius of thewire.

7. In a tool for wrapping a substantially square coil of strand onto aterminal having a substantially square cross-section,

a bit having a longitudinal axis for wrapping said coil upon rotation ofsaid bit on said axis relative to said terminal, said bit comprising agenerally cylindrical member having an end surface formed transversely 11 to said axis, said member also having a longitudinal groove extendingfrom said end surface in the outer periphery thereof for guiding saidstrand, said end surface having a curvilinear groove originating tangentthereto and extending congruent to the natural bending radius of saidstrand into said member into tangency with said longitudinal groove, anda lip formed in said member overhanging and curvilinear groove forguiding said strand from the longitudinal groove into the curvilineargroove to lay a substantially straight length of said strand on eachside of said terminal and form said square coil.

8. In a universal device for individually winding strands having largeand small diameters onto an elongated member;

universal bit means having a central longitudinal axis and a recessformed parallel with and eccentric to said axis for receiving saidelongated member, said bit means having a longitudinal groove forindividually maintaining a strand in a path parallel to said axis; and

means formed in said bit means for individually directing a strand fromsaid parallel path in ar arcuate path congruent to the natural bendingradius of the strand onto said elongated member, said means having aneffective surface corresponding to said arcuate path so that saidsurface continuously engages a strand advancing in the arcuate path,said surface having an arcuate configuration extending transversely tosaid arcuate path for receiving a strand having a large diameter. 9. Ina universal wrapping bit for providing squarewrap coils of variousfilaments having different diameters on terminals having squarecross-sections wherein the filaments assume a predeterminedconfiguration congruent to their respective natural bending radii duringwrapping on said terminals;

an elongated member having a flat end surface, a central longitudinalaxis, a peripheral groove provided on one side of said axis forindividually receiving said various filaments, a longitudinal recessformed through said end surface parallel to and on a side of said axisopposite to said one side for receiving said terminals, and means formedin the member tangent to said fiat end, the base of said groove, andsaid recess said means defining an arcuate guideway for guiding thefilaments in their respective natural bending radii to form saidsquare-wrap coils during said wrapping. 10. The method of manufacturinga bit for wrapping wire onto a terminal, said wire having acharacteristic of naturally assuming during said wrapping an arcuatebend congruent to the natural bending radius of said wire, comprisingthe steps of:

providing a bit blank having an end surface, a longitudinal grooveformed in the periphery thereof, and a recess for receiving saidterminal, and

abrading in said bit blank an arcuate surface having said naturalbending radius tangent to said recess, said end surface and said groove.

11. A method of manufacturing a bit for winding a solderless connectionbetween a connecting wire and a terminal wherein fabricating steps areperformed on a bit blank having an end surface, a longitudinal recessextending from the end surface, and a longitudinal groove formed in theperiphery and terminating at said end surface; said steps includingmoving the terminal and the bit blank relative to each other to insertthe terminal in the recess;

inserting a length of connecting wire into the groove;

rotating the bit and the terminal relative to each other to advance thelength of wire from the groove and wind the wire on the terminal, and

applying an abrasive compound to the advancing wire and the grooveadjacent to the end surface to form said bit having a wire guidewayconforming to the natural bending radius of the wire.

12. A method of manufacturing a wire winding bit from a generallycylindrical blank having an end surface, a longitudinal groove formed inthe periphery thereof and terminating at an opening in said end surface,and an axially extending recess; which comprises the steps of enclosingthe blank;

moving the enclosed blank and a terminal relative to each other toinsert the terminal in the recess;

providing an abrasive coating on the periphery of a length of wire;

feeding a length of the coated wire into the groove;

and

rotating the enclosed blank and the terminal relative to each other toadvance the coated wire out of the groove, through said opening, andonto the terminal to abrade and form in said blank a guideway having awire guide surface conforming to the natural bending radius of the wire.

13. A method of manufacturing a winding bit from a generally cylindricalblank having a longitudinal recess and a longitudinal slot extendingtoward an end surface wherein a standard bit having an end surface isprovided with .a longitudinal recess extending from the end surface anda longitudinal groove terminating in a chamferred edge joining the endsurface; which method comprise the steps of inserting the terminal intothe recess of the standard bit;

inserting a length of wire into said groove;

rotating the standard bit and the terminal relative to each other toadvance a first length of the wire through said groove, around thechamfered edge, and onto the terminal;

interrupting said relative rotation so that a second length of the wireremains received in said groove and said first length of the wireextends in an arcuate path congruent to the natural bending radius ofthe wire from said groove toward the terminal;

measuring said natural bending radius of said arcuate path, and

forming an arcuate surface having a radius conforming to said naturalbending radius tangent to the slot and the recess of the blank.

14. The method of manufacturing a bit for wrapping wire onto a terminal,said wire having a characteristic of assuming an arcuate path congruentto the natural bending radius of said wire during winding thereof onsaid terminal, comprising the steps of providing a bit blank having anend surface, a recess for receiving the terminal, and a longitudinalgroove formed in the periphery thereof and extending from said endsurface, the junction of said end surface and said groove forming acorner;

enclosing said bit blank within a sleeve to form a guideway with saidgroove;

moving the terminal into the recess,

feeding an indeterminate length of wire through said guideway,

securing a leading end of said wire to said terminal,

rotating said bit blank and said sleeve relative to the terminal toadvance the wire through the groove and around said corner on theterminal, and

stopping said rotation upon said Wire eroding said corner to form anarcuate surface congruent to the natural bending radius of said wire.

15. The method of wrapping a strand onto an elongated member, saidstrand having characteristics of naturally assuming a predeterminedcurved path corresponding to the natural bending radius of said strandduring said wrapping, said method including the steps of advancing saidstrand in the direction of the axis of said elongated member, directingsaid advancing strand transversely to said axis to form a section ofsaid strand into said predetermined curved path, and

engaging the entire length of said section to guide and wrap the wire insaid path onto said elongated member.

16. The method of Wrapping a Wire onto a terminal having a longitudinalaxis, wherein said Wire assumes a predetermined arcuate path having anatural bending radius during said Wrapping, which method comprises thesteps of advancing the Wire in the direction of the axis of saidterminal,

engaging and thrusting the advancing Wire transversely to said axis intosaid predetermined path corresponding to said natural bending radius ofthe Wire, and guiding said transversely thrust wire by continuously2,788,816 3/57 Wolf 15367 2,885,764 5/59 Shulters et al. 2427 3,006,56310/61 Bos et al. 2427 FOREIGN PATENTS 537,333 10/52 Canada.

OTHER REFERENCES IBM Technical Disclosure Bulletin, vol. 4, No. 8,January 1962, page 12.

CHARLES W. LANHAM. Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,213,894 October 26, 1965 John O. Etchison, Jr. et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3, line 46, after "wire" insert wrapping bit and methods ofmanufacturing the bit to column 5, lines longitudinal 5S and 56, for"longitudinally" read column 11, line 8, for "and" read said column 12,line 34, for "chamfere line 23, for

d" read "ar" read an chamferred -n Signed and sealed this 19th day ofJul 1966c (SEAL) Atteet:

EDWARD J. BRENNER ERNEST W. SWIDER Commissioner of Patents AttestingOfficer

1. IN A DEVICE FOR WINDING STRAND ONTO AN ELONGATED MEMBER, BIT MEANSHAVING A GROOVE FOR MAINTAINING THE STRAND IN AN AXIAL PATH, AND MEANSFORMED IN SAID BIT MEANS FOR DIRECTING THE STRAND FROM SAID AXIAL PATHIN AN ARCUATE PATH CONGRUENT TO THE NATURAL BENDING RADIUS OF THE STRANDONTO SAID ELONGATED MEMBER, SAID MEANS HAVING AN EFFECTIVE SURFACECORRESPONDING TO SAID ARCUATE PATH SO THAT SAID